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Master cylinder going out?

Discussion in 'Stock 1995 - 2001 Explorers' started by Darrman, August 1, 2011.

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  1. Darrman

    Darrman Active Member

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    City, State:
    Waxahachie, TX
    Year, Model & Trim Level:
    '92 Sport 4x4/2001 Sport
    I replaced all my brakes on the '01 Sport a couple weekends ago, went all out. Here is what I replaced:
    Rear pads with premium
    Rear antirattle clips
    Front rotors with new Motorcraft
    Front pads with premium ceramics
    Front antirattle clips
    Front slide pin boots
    Front bearings with new grease seal and dust caps
    Everything was cleaned and reassembled with fresh caliper grease/wheel bearing grease.
    Stopping power is tremendously improved!!
    BUT.....
    If I am riding the brake while doing low speeds, in other words parking lots, red lights, as I go to stop there will be good pedal pressure, then all of a sudden the pedal will start getting mushy and I can hear and feel the rotors grinding against the pads, like I lost pressure all of a sudden. It will continue to roll forward until I push real good on the pedal.
    I have checked, double checked, triple checked, even taking the pads back out and looking at the wear patterns, all are good and even.
    I have not bled the lines yet, but I did not open the lines either, so I dont understand how air could have gotten in. I did take a small amount from the resevior so I could push the pistons back in without overflow, but I know not to go to low and let it suck air. Plus I did not pump the brakes till after everything was done and the resevior was filled up again.
    I am not getting a abs light, and I did clean the sensors.
    So all this said, I am thinking its the M.C., I have a new one, but dont have a way to bleed the HCU.
    Any thoughts or opinions?
    Thanks!
     
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  3. jlsparky7

    jlsparky7 Well-Known Member

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    Year, Model & Trim Level:
    1996 5.0 XLT AWD
    Check for leaks a WHOLE LOT. Bleed the brakes, recheck for leaks. If there are no leaks then its your MC going out.
     
  4. mritz

    mritz New Member

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    City, State:
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    Year, Model & Trim Level:
    96 EB 5.0 V8 2x4
    Had this happen in my Expedition before
    when moving slow and applying bakes it was like I had none and had to pump them to stop
    actualy ended up being a bad sensor in the ABS never had a ABS light come on and only did it at slow speeds
    had the sensor replaced and brakes worked perfect
    dam scary when you push the pedal and have no brakes
     
  5. my98nnj

    my98nnj Well-Known Member

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    Year, Model & Trim Level:
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    You did all that brake work and never bleed (changed) the brake fluid, the blood of the system?

    Brake fluid is hygroscopic by nature (absorbs moisture) and should be changed with every brake job. No changing it is the cause of most internal brake system failures.
    Give the system a good bleed and see how it performs. If the problem still exists and your 100% certain the calipers, hoses, lines ect. and wheel bearings are in proper working order, then change the master cylinder.
     
  6. Darrman

    Darrman Active Member

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    '92 Sport 4x4/2001 Sport
    I know about moisture problems, I plan to change the fluid as soon as I can get some help. I will use a synthetic fluid, worked great in the clutch in the 92.
    The thing is I have not altered the lines in any way, so how could I get air in the lines?
    I never bleed a system till after I am sure that the new components are working proper, so it cuts down on figuring out what is wrong.
     
  7. swetrid

    swetrid Well-Known Member

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    Sounds like false abs activation to me, probably have a sensor dropping out. I have also sen people damage the tone ring area on 2wd rotors when they hammer the seal in.
     
  8. Darrman

    Darrman Active Member

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    hmm, i cleaned the sensors and backing plates with simple green, they were coated in dust from the cheapo pads that were on it, hopefully i didnt screw them up.
    I was careful not to hit the tone rings so hopefully thats not the issue.
    Is there any way to test the abs sensors?
     
  9. Darrman

    Darrman Active Member

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    Well it looks like it is the abs sensors, I ended up pulling the fuses out for the abs and the brakes work perfect just running conventional. So I am going to try cleaning them one more time and go from there.
     
  10. Paraphoe

    Paraphoe Go big or go home Elite Explorer

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    Year, Model & Trim Level:
    '97 XLT
    ABS = more trouble than it's worth? :rolleyes:

    Let us know if you have any luck cleaning or end up needing new sensors. I can't imagine that's cheap.
     
  11. Darrman

    Darrman Active Member

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    '92 Sport 4x4/2001 Sport
    I finally solved this problem last weekend, after replacing the sensors and getting nothing.
    Turns out it was the tone rings, I bought a set of drilled and slotted rotors and that fixed it right up. Its weird, I dont see any damage to the old tone rings, but it may be to slight to see.
     






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